Synthesis, characterization and evaluation of copper nanoparticles as agrochemicals against Phytophthora spp.

The colloidal solution of CuNPs (3±1 nm) was investigated the potential against Phytophthora spp. which cause economically crop diseases. Under in vitro test conditions, the inhibition of Phytophthora spp. mycelia growth at three concentrations of CuNPs (10, 20, 30 ppm) after 48 hours are 90.18%, 91.87% and 100%, respectively. These results provided a simple and economical.

Abstract—By using water as a solvent, copper

nanoparticles (CuNPs) have been synthesized from

copper sulfate via chemical reduction method in the

presence of trisodium citrate dispersant and

polyvinylpyrrolidone (PVP) as capping agent The

effects of the experimental parameters such as the

concentration of reducing agent (NaBH4), reaction

temperature, molar ratio of citrate/Cu 2+ and weight

percentage ratios of Cu 2+ /PVP on the CuNP sizes

were studied The size of CuNPs in a range of 31

nm was obtained at NaBH4 concentration of 0.2 M,

50 o C, citrate/Cu 2+ molar ratio of 1.0 and Cu 2+ /PVP

weight percentage of 5% The colloidal CuNPs were

characterized by using UV–Visible spectroscopy,

transmission electron microscopy (TEM), and X-ray

diffraction (XRD) techniques The colloidal solution

of CuNPs (3±1 nm) was investigated the potential

against Phytophthora spp which cause economically

crop diseases Under in vitro test conditions, the

inhibition of Phytophthora spp mycelia growth at

three concentrations of CuNPs (10, 20, 30 ppm) after

48 hours are 90.18%, 91.87% and 100%,

respectively These results provided a simple and

economical method to develop the

CuNPs-based-fungicide

Index Terms—antifungal activity, citrate

dispersant, copper nanoparticles, Phytophthora spp.,

PVP

Received: 12-11-2017; Accepted: 22-01-2018; Published:

31-12-2018

Hoang Minh Hao 1,* , Cao Van Du 2 , Duong Thi Ngoc Dung 2 ,

Cao Xuan Chuong 2 , Nguyen Thi Phuong Phong 3 , Nguyen Huu

Tri 4 , Pham Thi Bich Van 4 – 1 Faculty of Chemical and Food

Technology, HCMC University of Technology and Education,

2 Faculty of Pharmacy, Lac Hong University; 3 Faculty of

Chemistry, University of Science, VNUHCM; 4 Faculty of

Science, Nong Lam University

*Email: haohm@hcmute.edu.vn

1 INTRODUCTION

n recent years, nanoparticles have been extensively studied due to their unusual chemical and physical properties [1, 2] The effective applications of the nanoparticles generally depend on their size, shape and protecting agents which could be controlled by the preparation conditions [3] A number of different approaches to prepare metal nanoparticles such as

Cu, Ag, Pt, Au have been reported Some of these methods include photoreduction, chemical reduction using reducing agents in association with protecting agents [4-6]

Interestingly, the nanoparticles strongly exhibited the antifungal and antimicrobial activities [5, 6] Among them, copper nanoparticles (CuNPs) have much attention CuNPs showed a significant antifungal activity against various plant pathogenic fungi such as

Phytophthora, Corticium salmonicolor [7]

Phytophthora is a genus of plant-damaging

Oomycete whose member species are capable of causing enormous economic losses on crops The

genus Phytophthora approximately includes one hundred species [8] Phytophthora spp cause

diseases such as blight, stem rots, fruit rots

Worldwide crop losses due to Phytophthora

diseases are estimated to be multibillion dollars [9] Synthetic chemicals are currently used for inhibiting this fungal growth However,

Phytophthora spp are known to be able to

develop the resistance to chemicals rapidly [10] Thus, the discovery of new alternatives with

Hoang Minh Hao, Cao Van Du, Duong Thi Ngoc Dung, Cao Xuan Chuong,

Nguyen Thi Phuong Phong, Nguyen Huu Tri, Pham Thi Bich Van

Synthesis, characterization and evaluation of copper nanoparticles as agrochemicals against

Phytophthora spp

I

lower risk of resistance plays a major role for

controlling the pathogens as Phytophthora spp

As mentioned, CuNPs showed a significant

antifungal activity against Phytophthora In

addition, the cost to produce CuNPs is much

cheaper than the others such as silver

nanoparticles (AgNPs) and gold nanoparticles

(AuNPs) However, the studies on antifungal

activity of CuNPs have not yet received much

attention in Vietnam The low cost to prepare the

CuNPs is an advantage to use them in agriculture

as agrochemicals In this study, CuNPs were

prepared in water by chemical reduction method

in the presence of the sodium citrate dispersant

and polyvinylpyrrolidone (PVP) as protecting

agents The effects of the experimental parameters

such as the concentration of reducing agent

(NaBH4), reaction temperature, molar ratio of

citrate/Cu2+ and the weight percentage ratios of

Cu2+/PVP on the size of the CuNPs were

investigated UV–Visible spectroscopy,

transmission electron microscopy (TEM) and

X-ray diffraction (XRD) techniques were used to

characterize CuNPs The antifungal activity

against the growth of Phytophthora spp mycelia

was estimated under in vitro conditions on Potato

Dextrose Agar (PDA) medium

2 MATERIALSANDMETHODS

Materials

Copper (II) sulfate (CuSO4, 99.0%),

polyvinylpyrrolidone (Mw 58,000 g/mol),

(HOC(COONa)(CH2COONa)2.2H2O, 99.0%),

sodium borohydride (NaBH4, 98%) were

purchased from Acros Organics All reagents

were used without further purification Distilled

water was used as a solvent Phytophthora spp

were supplied by Laboratory Applications in

Microbiology, Institute of Tropical Biology,

Vietnam Academy of Science and Technology,

Linh Trung, Thu Duc, Ho Chi Minh City

Synthesis of CuNPs

The mixture including PVP (0.2 g), CuSO4 and

HOC(COONa)(CH2COONa)2.2H2O was

dissolved in 30 mL water The mixture was heated and stirred for 5 minutes The Cu2+ ions in the reaction mixture were then reduced to copper metal by the introduction of NaBH4 As thermal reduction proceeded, the blue solution turned to red, indicating the formation of the CuNPs for 10 minutes

Product characterization

UV–Vis absorption spectrum of the CuNPs solution was measured by Jasco V670 (Jasco Analytical Instrument) The colloidal CuNP solutions were diluted in water with the same concentrations prior to measuring UV-Vis spectra The UV-Vis spectra were scanned in a wavelength range from 500 to 800 nm TEM images were measured by JEM-1400 version (JEM-1400, JEOL) The samples for TEM measurement were prepared by dropping CuNPs solution onto a carbon-coated copper grid The histogram of the particle-size distribution and the average diameter were obtained by measuring particles The XRD result was characterized using D8 advanced Bragg X-ray (D8 Advance, Brucker) with Cu Kα radiation For sample handling, glass slide was used as a substrate for measurement Leaned substrate was covered with the colloidal CuNPs solution and dried in air

Determination of the antifungal activity

The antifungal activity against Phytophthora spp was estimated by using the in vitro plate

dilution method The colloidal CuNP solutions with various concentrations (10, 20, 30 ppm) were mixed with melting PDA medium to obtain a 15

mL total volume in Petri dishes The control dishes contained 50 ppm of PVP, or 50 ppm of copper sulfate without colloidal CuNPs The

fungus Phytophthora spp strain was activated by

inoculation the mycelia on PDA dish at 37oC, 72 hours Then, the activated fungus was split into small pieces (5 mm x 5 mm) The treatments were performed by putting the small piece of active fungus in central of petri plates, wrapped with parafilm and incubated at 37oC The diameters of the colony growth of the control and CuNP samples were observed after 24 and 48 hours Each treatment for each concentration of CuNPs

was replicated three times The inhibition of the

growth of the mycelia was estimated by

measuring the colony diameter and calculated by

formula: growth inhibition (%) = (d1−d2/d1) ×

100, where d1 and d2 are colony diameters of the

control and CuNPs contained samples,

respectively

3 RESULTSANDDISCUSSION

Characterization of CuNPs

The formation of CuNPs is confirmed by the

powder X-ray diffraction (XRD) Figure 1

showing the peak positions with high crystallinity

at 43.2o, 50.4o, and 74.0o in XRD pattern are

consistent with metallic copper These peaks

correspond to the typical face-centered cubic of

copper with miller indices at (111), (200), and

(220) which are in good agreement with the

literature values [5, 11-14] This result also

indicated that copper oxides (Cu2O and CuO)

were not formed in the synthetic process

Furthermore, the color of solution had changed

from blue to reddish This observation revealed

that the efficiency of reduction of copper salt

(Cu2+, blue) into copper metal (Cu0, reddish) was

significant

Fig 1 X-Ray diffractogram of CuNPs

Effect of reducing agent concentration on the

size of copper nanoparticles: Sodium borohydride

(NaBH4) was used as a reducing agent to prepare

CuNPs Reaction temperature (50oC), and the

amount of PVP (0.2 g) were kept constant The

amounts of copper salt and trisodium citrate were

used to ensure that the weight percentage ratio of

Cu2+/PVP and the molar ratio of citrate/Cu2+ were

always 3% and 0.5, respectively The reaction time was 15 minutes The reducing agent of NaBH4 allows a variation of concentration within

a range of 0.1 – 0.5 M Figure 2 illustrated the UV-Vis spectra of colloidal CuNP solutions with various concentrations of NaBH4 The results showed that the surface plasmon resomance of CuNPs shifted to shorter wavelengths with increasing the NaBH4 concentration (from 583 nm

at 0.1 M to 570 nm at 0.2 M) However, the maximum absorption peaks shifted to longer wavelengths (574, 576 and 582 nm) at higher concentrations (0.3, 0.4 and 0.5 M) of reducing agent

Fig 2 UV-Vis spectra of colloidal CuNP solutions at various

concentrations of NaBH 4

This observation could be attributed to an increase the CuNP sizes at higher concentrations (> 0.2 M) [5, 6, 18] The CuNPs were generated

in soltution through two stages The copper nuclei

is firstly generated and then was the growth of CuNPs [18] It is thus important to control the preparation process that copper nuclei must generate faster and grow up slower With increasing the concentration of NaBH4, the reaction conversion rate of copper sulfate increased, the amount of copper nuclei rose, and small particle size powders were obtained However, an excess number of copper nuclei would be generated when the reducing agent concentration was high This resulted in an agglomeration of nuclei and a growth of the particle size Thus, the optimal concentration of NaBH4 was 0.2 M

Effect of reaction temperature on the size of

copper nanoparticles

Concentration of NaBH4 (0.2 M), the weight

percentage ratios of Cu2+/PVP (3%) and the molar

ratio of citrate/Cu2+ (0.5) were fixed in the

experiments The reaction temperature was varied

in a range from 40 to 80oC The UV-Vis spectra

of colloidal CuNP solutions were given in Figure 3

The positions of maximum peaks had a decrease

in wavelength with increasing the reaction

temperature from 40 to 60oC (586 nm at 40oC,

575 nm at 50oC and 570 nm at 60oC) However,

an increase in temperature from 60 to 80oC, the

opposite shifts was obtained (575 nm at 70oC and

580 nm at 80oC) The results could be attributed

to the change of CuNP sizes with varying the

temperature The CuNP size decreased when the

temperature grew up to a certain range The

nucleation rate was greater than the growth rate

when the temperature increased within a range

from 40 to 60oC At higher temperatures (> 60oC),

the viscosity of the solution decreased and the

growth rate enhanced due to CuNP collisions As

a result, the size of CuNPs increased with the

increasing the reaction temperature [6, 18, 19] At

lower temperatures, the formation of CuNPs was

not favorable Therefore, the optimal reaction

temperature was selected at 50oC

Fig 3 UV-Vis spectra of colloidal CuNP solutions at different

temperatures

Effect of citrate/copper salt ratio on the size of

copper nanoparticles

In order to investigate the effect of citrate/Cu2+

ratios on the size of CuNPs, the reaction mixture

was conducted at 50 oC, the concentration of

reducing agent (NaBH4) was 0.2 M, and the amount of PVP was 0.2 g while the molar ratio of citrate/Cu2+ varied in a range from 0.0 to 2.0 Figure 4 depicted UV–Vis absorption spectra of colloidal CuNP solutions in a range of molar ratio

of citrate/Cu2+ from 0.0 to 2.0 In the presence of citrate dispersant, the maximum peaks of CuNPs shifted to shorter wavelength with increasing molar ratio of citrate/Cu2+ This observation could result from a change in nanoparticle size However, absorbed wavelengths ( 567 nm) were insignificantly different when using molar ratios ranging from 1.0 to 2.0

Effect of the weight percentage ratio of copper salt to PVP on the size of copper nanoparticles

During the synthetic process, the reaction temperature (50oC) and the reducing agent concentration (0.2 M), and the amount of PVP (0.2 g) were kept constant The weight percentage ratios of Cu2+ to PVP were varied in a range from

1 to 13% The amount (mole) of citrate was also varied according to the variation of the copper salt amount in solutions so that the molar ratio of citrate/Cu2+ (1.0) was always constant The UV-Vis spectra of the CuNP solutions were given in Figure 5 The results showed that the absorbance

at maximum peaks increased with increasing the weight percentage ratio of Cu2+ to PVP from 1 to 11% The position of the maximum peaks in a region of 567–570 nm When the Cu2+/PVP ratio reached 13%, the peak shifted to longer wavelength (573 nm) This result showed that the size of CuNPs increased at the Cu2+/PVP ratio of

13%

Fig 4 UV-Vis spectra of the colloidal CuNP solutions with

different molar ratios of citrate/copper salt

Fig 5 UV–Vis spectra of colloidal CuNP solutions with

various weight percentage ratios of Cu 2+ to PVP

TEM images of samples

The TEM images of CuNPs shown in Figure 6 confirmed the correlation between the citrate concentration and the size of the produced CuNPs The changes of size caused the UV-Vis spectra to shift to shorter wavelengths as mention above In the absence of citrate, average diameter

of CuNPs was in a range of 207 nm, whereas its diameter appeared in a range of 31 nm at molar ratio of citrate/Cu2+ of 1.0 Thus, this ratio of citrate to copper salt was optimized at 1.0 to prepare CuNPs for biological tests Moreover, these results confirmed that CuNPs with smaller sizes absorb at shorter wavelengths in UV–Vis spectra

Fig 6 TEM images of CuNPs prepared in the absence (a) and the presence (b) of citrate dispersant The molar ratio of

citrate/Cu 2+ is 1.0

Fig 7 TEM images of CuNPs prepared in various ratios of Cu2+ /PVP: (a) 5%, (b) 9% and (c) 11%

Figure 7 showed the TEM images and size

distribution of the copper nanoparticles which

were synthesized with different of ratio of

Cu2+/PVP At ratio of Cu2+/PVP=5% (Fig 7a), the

copper nanoparticles were synthesized mainly in

spherical, uniform distribution with the size 3 ± 1

nm When the ratio of Cu2+/ PVP increased to 9 %

and 11% (Fig 7b, 7c), the copper nanoparticles

were prepared in an approximate spherical shape,

higher concentration and cluster formation

because of high concentration of nanoparticles

formed However, due to the synergistic of PVP

and citrate, the nanoparticles were prepared with

small size, the size in range of 4±1 nm and 3±1

nm, respectively

Synergistic effect of citrate dispersant and

PVP capping agent: Polyvinylpyrrolidone (PVP)

has been extensively used as a capping polymer to

protect colloidal solution containing metallic

nanoparticles [5, 6] However, the bulky polymer

is ineffective to coat all surfaces of the metallic

nanoparticles These results in an outgrowth in

size of particles were due to their collision To

prevent this disadvantage, a molecular protecting

agent like trisodium citrate could be used A

certain amount of trisodium citrate molecules is

adsorbed on the surface of metallic nanoparticles

As a consequence, the aggregation of

nanoparticles due to their collision was

significantly reduced Furthermore, it has been

hard to prepare these small and uniform-sized

metallic nanoparticles in the sole presence of

capping polymers or citrate dispersant [6] The

synergistic effect of citrate dispersant and capping

polymer has been expected to control size growth

of CuNPs as demonstrated in Figure 8 Citrate and

PVP work as size controller and polymeric

capping agents, because they hinder the nuclei

from aggregation through negative charge and

polar groups, which strongly absorb the CuNPs on

the surface via electrostatic interactions

coordination bonds [15, 16]

Fig 8 A demonstration of the synergistic effect of citrate

dispersant and PVP capping polymer on controlling size growth of CuNPs Left figure depicts the formation of complexes of copper ions and citrate or PVP The synergistic effect of citrate and PVP is given in the right figure

Stability of colloidal CuNP solutions: The colloidal CuNP solutions were synthesized by using optimized conditions described above Figure 9 showed that the positions of peaks at maximum absorption wavelengths (569 nm) were not changed after 1 and 3 months of storage This observation confirmed that the CuNPs were stable during storage time, i.e., the size of CuNPs was not changed However, the maximum peaks shifted to 579 nm after 5 and 6 months This result revealed that the size of CuNPs increased with increasing the storage time Furthermore, there was no peak of Cu2O at 450 nm, i.e., the CuNPs were not oxidized during the storage period

Fig 9 UV-Vis spectra of the colloidal CuNP solutions at

different storage times

CuNPs inhibit Phytopthora spp in vitro

Basing on optimized experiments above, the

CuNPs having an average diameter in range of

31 nm were prepared The potential of the

colloidal CuNP solutions at various

concentrations (10, 20, 30 ppm) were estimated

against Phytophthora spp Figure 10 showed the

antifungal ability against Phytophthora spp After

48 hours of the incubation, the highest antifungal

activity was observed at the CuNP concentration

of 30 ppm (100%) At lower concentrations of 10

ppm and 20 ppm, CuNPs were less effective with

90.18% and 91.87% of fungal growth inhibition,

respectively

Fig 10 The fungal growth inhibition of CuNPs at various

concentrations against Phytophthora spp after 48 hours of

incubation CuNPs were not added to control

Nanoparticles can be currently used as

alternatives to chemical pesticides Most of CuNP

studies have focused on antibacterial activities

and to a lesser extent on antifungal activities

Under in vivo condition, the chromosomal DNA

degradation in E coli started within 30 minutes of

treatment with CuNPs, and more degradation

occurred with the increasing of the nanoparticle

exposure time The mechanism of antibacterial

activity of CuNPs in E coli cells has been

proposed The copper ions (Cu2+) attributed to be

the main effector for DNA degradation, the

nascent ions were generated from the oxidation of

metallic CuNPs when they were in the vicinity of

agents, namely cells, biomolecules or medium

components [17] To the best of our knowledge no study has been reported to explore the mechanism

of the growth inhibition of CuNPs on

Phytophthora spp

4 CONCLUSION CuNPs were prepared via chemical reduction method under the presence and the absence of citrate dispersant and PVP capping polymer The purity and stability of the CuNPs were revealed

by X-ray diffraction (XRD), UV–Vis spectroscopy and TEM techniques The effects of the concentration of reducing agent, the reaction temperature and the ratios of copper salt to protecting agents on the CuNP sizes were investigated In order to obtain a small size distribution (31 nm), the experimental conditions were optimized The optimal concentration of NaBH4, and reaction temperature were 0.2 M and

50oC, respectively The ratios of Cu2+ to citrate (citrate/Cu2+-molar ratio) and PVP (Cu2+ /PVP-weight percentage) were 1.0 and 5%, respectively

In solution, citrate and PVP played as size controller and capping agents, they impeded the aggregation of CuNPs by forming coordination bonds via negative charge and polar groups The CuNPs having the size of 31 nm were estimated the inhibition of the fungal growth and exhibited a high potency of the antifungal against

Phytophthora spp under in vitro treatments The

result showed a complete inhibition of the

Phytophthora spp mycelia growth at 30 ppm

This result demonstrated that CuNPs not only were used as alternatives to chemical pesticides against Phytophthora spp without any phytotoxicity but also can be applied as a novel antifungal agent in agriculture to control the plant pathogenic fungi

Acknowledgment: The authors are thankful

to Lac Hong University and Ho Chi Minh City University of Technology and Education for support Laboratory Applications in Microbiology, Institute of Tropical Biology, Vietnam Academy of Science and Technology, Linh Trung, Thu Duc, Ho Chi Minh City is gratefully acknowledged

REFERENCES

[1] G Schmid, Clusters and Colloids: From Theory to

Applications, VCH: Weinheim, 1994

[2] B C Gates, Supported Metal Clusters: Synthesis,

Structure, and catalysis, Chem Rev, vol 95, no 3, pp 511–

522, 1995

[3] H Bonnemann, W Brijoux, R Brinkmann, R Fretzen, T

Joussen, R Koppler, B Korall, P Neiteler, J Richter,

Preparation, Characterization, and Application of fine metal

particles and metal colloids using hydrotriorganoborates, J

Mol Catal, 86, 1–3, pp 129–177, 1994

[4] H.H Huang, X.P Ni, G.L Loy, C.H Chew, K.L Tan, F

C Loh, J.F Deng, G.Q Xu, “Photochemical Formation of

silver nanoparticles in poly(N-Vinylpyrrolidone)”,

Langmuir, vol 12, no 4, pp 909–912, 1996

[5] V.D Cao, P.P Nguyen, V.Q Khuong, C.K Nguyen, X.C

Nguyen, C.H Dang, N.Q Tran, “Ultrafine copper

nanoparticles exhibiting a powerful antifungal/killing

activity against Corticium Salmonicolor, Bull Korean

Chem Soc, vol 35, no 9, pp 2645–2648, 2014

[6] V.D Cao, N.Q Tran, T.P.P Nguyen, “Synergistic Effect of

Citrate Dispersant and Capping Polymers on Controlling

Size Growth of Ultrafine Copper Nanoparticles”, Journal

of Experimental Nanoscience, vol 10, no 9, pp 576–587,

2015

[7] M Ali, B Kim, K.D Belfield, D Norman, M Brennan, G

S Ali, Inhibition of Phytophthora parasitica and P Capsici

by silver nanoparticles synthesized using aqueous extract of

Artemisia absinthium, Disease Control and Pest

Management, 105, 9, 1183-1189, 2015

[8] L.P.N.M Kroon, H Brouwer, A.W.A.M de Cock, F

Govers, “The genus Phytophthora anno”, Phytopathology,

vol 102, no 4, pp 348–364, 2012

[9] S Wawra, R Belmonte, L Lobach, M Saraiva, A

Willems, P.V West, “Secretion, delivery and function of

oomycete effector proteins” , Current Opinion in

Microbiology, vol 15, no 6, pp 685–691, 2012

[10] R Childers, G Danies, K Myers, Z Fei, I M Small,

W E Fry, “Acquired Resistance to Mefenoxam in

Sensitive Isolates of Phytophthora infestans,

Phytopathology”, 105, 3, pp 342–349, 2015

[11] S.N Masoud, D Fatemeh, M Noshin, “Synthesis and characterization of metallic copper nanoparticles via

thermal decomposition”, Polyhedron, vol 27, no 17, pp

3514–3518, 2008

[12] N.A Dhas, C.P Raj, A Gedanken, “Synthesis, characterization, and properties of metallic copper

nanoparticles”, Chem Mater, vol 10, no 5, pp 1446–

1452, 1998

[13] J.A Creighton, D.G Eadon, “Ultraviolet-Visible

absorption spectra of the colloidal metallic elements”, J

Chem Soc., Faraday Trans, vol 87, no 24, pp 3881–

3891, 1991

[14] S Panigrahi, S Kundu, S.K Ghosh, S Nath, S Praharaj, S Basu, T Pal, Selective one-pot synthesis of copper nanorods under surfactantless condition,

Polyhedron, vol 25, no 5, pp 1263–1269, 2006

[15] W Yu, H Xie, L Chen, Y Li, C Zhang, “Synthesis and characterization of monodispersed copper colloids in

polar solvents”, Nanoscale Res Lett, vol 4, no 4, pp 465–

470, 2009

[16] A Sarkar, T Mukherjee, S Kapoor, PVP-Stabilized copper nanoparticles:  a reusable catalyst for “click” reaction between terminal alkynes and azides in

nonaqueous solvents, J Phys Chem C, pp 112, no 9, pp

3334–3340, 2008

[17] A.K Chatterjee, R Chakraborty, T Basu, “Mechanism

of antibacterial activity of copper nanoparticles”,

Nanotechnology, vol 25, no 13, pp 1–12, 2014

[18] Q.L Zhang, Z.M Yang, B.J Ding, X.Z Lan, Y.J Guo,

“Preparation of copper nanoparticles by chemical reduction

method using potassium borohydride”, Trans Nonferrous

Met Soc China, vol 20, no 1, pp 240–244, 2010

[19] D.X Zhang, H Xu, Y.Z Liao, H.S Li, X.J Yang,

“Synthesis and characterisation of nano-composite copper oxalate powders by a surfactant-free stripping–precipitation

process”, Powder Technology, vol 189, no 3, pp 404–408,

2009

Tổng hợp, xác định cấu trúc hóa học và

khảo sát hoạt tính kháng nấm

Phytophthora spp của hạt đồng nano

Hoàng Minh Hảo1,*, Cao Văn Dư2, Dương Thị Ngọc Dung2, Cao Xuân Chương2,

NguyễnThị Phương Phong3, Nguyễn Hữu Trí4, Phạm Thị Bích Vân4

1Khoa Công nghệ Hóa học và Thực phẩm, Trường Đại học Sư phạm Kỹ thuật TP HCM,

2Khoa Dược, Trường Đại học Lạc Hồng, 3Khoa Hóa học, Trường Đại học Khoa học Tự nhiên, ĐHQG-HCM,

4Khoa Khoa học, Trường Đại học Nông Lâm

*Tác giả liên hệ: haohm@hcmute.edu.vn

Ngày nhận bản thảo: 12-11-2017; Ngày chấp nhận đăng: 22-01-2018; Ngày đăng: 31-12-2018

Tóm tắt—Các hạt đồng nano (CuNPs) đã được

tổng hợp trong dung môi nước bằng phương pháp

khử hóa học trong sự hiện diện của các tác chất

phân tán trisodium citrate và chất bảo vệ

polyvinylpyrrolidone (PVP) Ảnh hưởng của nồng

độ chất khử (NaBH4), nhiệt độ phản ứng, tỷ lệ mol

citrate/Cu 2+ và tỷ lệ khối lượng Cu 2+ /PVP lên kích

thước các hạt đồng nano đã được khảo sát Kích

thước 31 nm của các hạt đồng nano đạt được tại

nồng độ chất khử là 0,2 M, nhiệt độ phản ứng là

50 o C, tỷ lệ mol citrate/Cu 2+ là 1,0 và tỷ lệ khối

lượng Cu 2+ /PVP là 5% Đặc điểm hạt đồng nano

được xác định bằng phổ tử ngoại-khả kiến (UV– Vis), chụp ảnh dưới kính hiển vi điện tử truyền qua (TEM) và nhiễu xạ tia X (XRD) Hoạt tính kháng nấm của các hạt đồng nano (kích thước 31 nm) được thử nghiệm đối với nấm

Phytophthora spp Thử nghiệm in vitro cho thấy,

chế phẩm đồng nano tại các nồng độ 10, 20 và 30 ppm đã ức chế 90,18%, 91,87% và 100% sự phát

triển của tơ nấm Phytophthora spp sau 48 giờ

Kết quả này là cơ sở để phát triển chế phẩm diệt nấm đơn giản, kinh tế dựa trên các hạt đồng nano

Từ khóa—hoạt tính kháng nấm, chất phân tán citrate, hạt đồng nano, Phytophthora spp., PVP